JP2000244564A - Multimedia communication packet sequence control method, multimedia communication terminal, and recording medium recording multimedia communication packet sequence control program - Google Patents

Abstract

(57) [Summary] [Problem] To perform normal video / audio communication even if a packet order change occurs. SOLUTION: An ICMP ECHO packet is transmitted to a communication partner, and an ICMP ECHO Re from the communication partner is transmitted.
Receive the ply packet. ICMP ECHO Packet Transmission Time and ICMP ECHO Reply
An average packet transmission time is calculated from the packet reception time. The buffer size of the buffer is adjusted so that packets arriving within the average transmission time can be received, and the received packets are stored in the buffer. If the sequence numbers of the packets are not consecutive, the buffer size of the buffer is adjusted again so that the packets can be received for the average transmission time. Next, the received packet is stored in the buffer, and the sequence number of the packet is checked. If there are packets with consecutive sequence numbers in the buffer, the order of the packets is changed so that the sequence numbers are consecutive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a packet order control method for multimedia communication.

[0002]

2. Description of the Related Art In order to perform real-time two-way communication of video and audio in a TCP / IP protocol environment generally used in a current LAN, an international standard ITU is used.
-TH. 323 or the original method (×××××××××
It is necessary to use the communication protocol used in XXXX.

[0003]

In a TCP / IP protocol environment, ITU-T H.264 is used. 323 or ×××
In the communication protocol (hereinafter, FM-C100L protocol) used in xxxxxx, in order to realize real-time bidirectional communication with video and audio, OSI (Open Systems) is used when establishing a communication path. In
Transmission (TCP) of the transport layer (layer 4) of the terconnection reference model
n Control Protocol) packet
UDP (User Datagram) for video and audio communication
m Protocol) packet is used. TCP
Packets are a connection-type protocol that provides highly reliable communication means. Even if a packet is lost due to a collision with a packet due to another communication, the packet is reliably transmitted sequentially by a retransmission procedure or the like. On the other hand, UDP
Since the first priority of the packet is to perform high-speed packet transmission, even if a packet is lost or the packet order is changed due to a collision, a retransmission procedure is not performed, and reliable data transmission is not guaranteed.

Accordingly, ITU-TH. 323 and FM-
In the C100L protocol, a header is provided in a UDP packet, and a sequential number is provided in the header. This sequential number is monitored, and if the continuity is broken, it is determined that packet collision or discard has occurred.
Reduce the video transmission speed. This mechanism is FM-C
The standard is implemented in the 100L protocol, and the ITU
-TH. H.323 can also be realized by combining an RTP / UDP packet to which a sequential number is assigned and a gatekeeper for monitoring the traffic volume.
With this function, the frequency of collisions is reduced by reducing the amount of traffic on the LAN, and appropriate real-time communication of video and audio is enabled.

[0005] ITU-TH. 323 or FM-C100
The L protocol realizes real-time two-way communication of video and audio in a TCP / IP protocol environment used for general purposes, and a LAN on which the TCP / IP protocol operates.
Not all environments will work properly. SOHO (Smal) using a relay line such as a router and a dedicated line
l Office Home Office) environment,
W in which routers are connected in multiple stages using trunk lines such as dedicated lines
An AN environment is a LAN on which the TCP / IP protocol operates.
(WAN) environment, but depending on router performance, UD
An order change of the P packet occurs (FIG. 3). For example, if the 2 × B channel of the INS net 64 is used as a relay line between routers, and the Nth size of the transmitted UDP packet is larger than the total size of the (N + 1) th and (N + 2) th, the 1B channel is used. While the N-th packet is being transmitted, the (N + 1) -th and (N + 2) -th packets are transmitted on the 2B channel, and as a result, the order of the packets may be changed. In the case where routers are connected in multiple stages and there is even one router with inferior performance, packet order may be changed due to packet delay. As described above, when the order of the UDP packets is changed, the ITU-T H. 323 and FM
In the -C100L protocol, it is determined that the packet has been discarded, and only the transmission speed of the video is reduced, but the packet rearrangement phenomenon is not improved. Therefore, normal video / audio communication is not realized.

An object of the present invention is to provide a packet order control method and a terminal for multimedia communication capable of performing normal video / audio communication even when the order of UDP packets is rearranged.

[0007]

According to the present invention, TCP / I
ICMP (I
internet Control Message P
protocol is dynamically controlled using a communication protocol and the packet is sequentially checked. If a UDP packet cannot be received sequentially, the packet is discarded in the middle. It is accurately determined whether the replacement has been performed. Therefore, in a TCP / IP environment, ITU-TH. When real-time two-way communication of bequests and voices is performed using the H.323 or FM-C100L protocol, normal operation can be performed even if the order of UDP packets is changed. The procedure of the present invention is described below.

First, in order to measure a transmission time of a packet between terminals performing communication, an ICMPECHO packet is transmitted to a communication partner. The ICMP ECHO packet transmission unit is provided on the side that transmits video / audio data.
The sending interval of ICMP ECHO packets is ICM
It is assumed that the communication amount of the P packet is extremely small compared to the entire communication environment and does not affect the communication environment.

Next, an ICMP ECHO is sent from the communication partner.
Since the Reply packet is returned, ICMP EC
HO packet transmission time and ICMP ECHO Re
The average transmission time of the packet is calculated from the reception time of the ply packet. The transmission time is measured not only before the real-time video / audio communication is performed, but also during the communication and when the continuity of the packet sequence numbers in the buffer is interrupted. This is because when the traffic volume increases, the communication environment including the router and the transmission path becomes overloaded, and the response of packet transmission may decrease. In addition, an upper limit of the transmission time is set in advance, and when the value of the average transmission time is larger than the set upper limit, the preset upper limit is set as the average transmission time.

Since the average transmission time dynamically changes depending on the communication environment, the buffer size is dynamically adjusted so that packets arriving in the average transmission time range can be buffered. Since the upper limit is set in advance for the average transmission time, the physical size of the buffer is limited by the value of the average transmission time.

Next, the sequential number of a packet arriving at the buffer on the receiving side when communication is actually started is monitored. If continuity is maintained, packets are sequentially passed to the next processing unit without performing buffer processing. If the continuity breaks, either because the packet was dropped in the middle of the channel or the order was changed,
A process of determining whether to discard or change the order is performed. If there is enough space in the buffer to receive the next packet, the next received packet is stored in the buffer. A sequential check of the packets is performed, and if a corresponding packet is found, the order is changed in the buffer to ensure continuity. If the corresponding packet is not found and there is not enough space to receive the next packet, it is determined that the packet has been discarded.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a multimedia communication terminal according to an embodiment of the present invention includes a camera 11 and a microphone 12.
, A video signal encoding unit 13 and an audio signal encoding unit 14
Multiplexing unit 15 and sequential number assigning unit 16
, ICMP ECHO packet transmitting unit 17 and IC
MP ECHO Reply packet transmission unit 18, average transmission time calculation unit 19, control unit 20, buffer 21
And ICMP ECHOReply LAN I / F
(Interface) 22, a packet transmission unit 23,
It comprises a video / audio separation section 24, a video signal expansion section 25, an audio signal expansion section 26, a monitor 27, and a speaker 28.

Image taken by camera 11, microphone 12
Are collected by the video signal encoding unit 13 and the audio signal encoding unit 14, respectively, are multiplexed by the multiplexing unit 15, are sequentially assigned by the sequential number assigning unit 16, and are assigned LAN IDs. / F22. The ICMP ECHO packet transmitting unit 17
Sends a CMP ECHO packet to the communication partner and sends the IC
The MP ECHO Reply packet receiving unit 18 receives an ICMP ECHO Reply packet from a communication partner. The average transmission time calculation unit 19 is ICMP EC
HO packet transmission time and ICMP ECHO Re
ply Calculates the average packet transmission time from the packet reception time. The control unit 20 dynamically changes the size of the buffer 21 based on the average transmission time and checks the sequential number of the received UDP packet. The ICMP ECHO Reply packet transmitting unit 23 transmits an ICMP ECHO Reply packet when receiving the ICMP ECHO Reply packet. The video / audio separation unit 24 separates video and audio from the UDP packets in the buffer 21 respectively. The video signal expansion unit 25 and the audio signal expansion unit 26 expand the video signal and the audio signal, respectively, and output them to the monitor 27 and the speaker 28, respectively.

FIG. 2 is a flowchart showing a packet order control procedure in this embodiment.

First, at step 31, ICMP ECHO
ICMP ECH from the packet sending unit 17 to the communication partner
O Send a packet. In step 32, the ICMP ECHO Reply packet from the communication
The MP ECHO Reply packet receiving unit 18 receives the packet. In step 33, the average transmission time calculation unit 19
Transmission time of CMP ECHO packet and ICMP E
The average transmission time of the packet is calculated from the reception time of the CHO Reply packet. The control unit 20 performs the following processing. In step 34, the buffer size of the buffer 21 is adjusted so that packets arriving within the average transmission time can be received. In step 35, the received UDP packet is stored in the buffer 21. In step 36, the sequence number of the UDP packet is checked. If the sequence numbers of the UDP packets are not consecutive, the buffer size of the buffer 21 is again set to U for the average transmission time in step 37
Adjust so that DP packets can be received. Step 3
In step 8, the received UDP packet is stored in the buffer 21, and in step 39, the sequence number of the UDP packet is checked. If there is a UDP packet having a continuous sequence number in the buffer 21, the order of the UDP packets is changed in step 40 so that the sequence numbers are continuous. UDP with consecutive sequence numbers in buffer 21
If there is no packet, it is checked in step 41 whether there is enough space in the buffer 21 to receive the next UDP packet. If there is a vacancy, the process returns to step 38 and the next packet is stored in the buffer 40. If there is no room,
In step 41, reduce the amount of video data to be transmitted or
A request is made to the other party to reduce the amount of video data to be sent.

The processing shown in FIG. 2 is recorded on a recording medium such as an FD (floppy disk), CD-ROM, MD (magneto-optical disk) as a packet order control program, and is executed by a personal computer or the like. You can also.

[0018]

As described above, according to the present invention, even if a sequence change occurs in the middle of a communication path or a packet delay occurs in the middle of a communication, the sequence change processing is performed dynamically, and Even if discarding occurs, normal discarding is performed without confusing with the order changing process, so that normal video / audio communication can be performed even if the packet order changing occurs.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a multimedia communication terminal according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a packet order control procedure.

FIG. 3 is an explanatory diagram of the occurrence of a change in the order of UDP packets.

[Explanation of symbols]

Reference Signs List 11 camera 12 microphone 13 video signal encoding unit 14 audio signal encoding unit 15 multiplexing unit 16 sequential number assigning unit 17 ICMP ECHO packet sending unit 18 ICMP ECHO Reply packet receiving unit 19 average transmission time calculating unit 20 control unit 21 buffer 22 LAN I / F 23 ICMP ECHO Reply Packet transmission unit 24 Video / audio separation unit 25 Video signal expansion unit 26 Audio signal expansion unit 27 Monitor 28 Microphone 31-42 Step

Continued on the front page F term (reference) 5C059 KK34 RB02 RC22 SS06 SS20 TA16 TC15 TD12 UA32 UA38 5K030 GA11 HB00 HB19 HB21 HC01 JA10 JT10 KA02 LA08 MA13 MB06 MB13 MB15 5K034 AA05 CC02 CC05 MM08 QQ04 9A001 CC06 CC07 CC07 CC01

Claims (3)

[Claims] Sending an ICMP ECHO packet to a communication partner; and an ICMP ECHO Reply from the communication partner.
Receiving the packet, calculating an average transmission time of the packet from the transmission time of the ICMP ECHO packet and the reception time of the ICMP ECHO Reply packet, and dynamically adjusting the buffer size so that the packet arriving within the average transmission time can be received. Adjusting the packet number, storing the packet received from the communication partner in a buffer, checking whether the sequence numbers of the received packets are consecutive, and if the sequence numbers of the received packets are not consecutive,
Dynamically adjusting the buffer size so that packets arriving within the average transmission time can be received; storing the next packet received from the communication partner in a buffer; and the next received packet sequence. Checking whether the numbers are consecutive and, if a corresponding packet is found in the buffer, replacing the packets in the buffer so that the sequence numbers are consecutive, and not finding the corresponding packet in the buffer If there is enough space in the buffer to receive the next packet, it returns to the step of storing the next received packet in the buffer. Reduce the amount of video data Multimedia communication packet sequencing comprising the step of requesting a reduction in the amount of video data. 2. A multimedia communication terminal for transmitting an ICMP ECHO packet to a communication partner.
A CMP ECHO packet sending unit, and an ICMP ECHO Reply from the communication partner.
ICMP ECHO Reply to receive packets
Packet receiving unit, ICMP ECHO packet sending time and ICMP
An average transmission time calculation unit for calculating an average transmission time of a packet from the reception time of the ECHO Reply; and a buffer size dynamically adjusted so that a packet arriving within the average transmission time can be received. Storing the packets in a buffer, checking whether the sequence numbers of the received packets are consecutive, and, if the sequence numbers of the received packets are not consecutive, setting the buffer size to be able to receive packets arriving within the average transmission time; Dynamically adjusts, stores the next packet received from the communication partner in the buffer, checks whether the sequence number of the next received packet is continuous, and if a corresponding packet is found in the buffer, Replace the packets in the buffer so that the sequence numbers are consecutive, and If the corresponding packet is not found in the file, it is determined whether there is enough space in the buffer to receive the next packet, and if so, the next received packet is stored in the buffer, and the buffer is empty enough to receive the next packet. A multimedia communication terminal having a control unit for reducing the amount of video data to be transmitted if there is no data, or requesting a communication partner to reduce the amount of video data to be transmitted. 3. A procedure for sending an ICMP ECHO packet to a communication partner, and an ICMP ECHO Reply from the communication partner.
Receiving a packet, calculating an average packet transmission time from an ICMP ECHO packet transmission time and an ICMP ECHO Reply packet reception time, and dynamically adjusting a buffer size so that a packet arriving within the average transmission time can be received. Adjusting the sequence, storing the packets received from the communication partner in a buffer, checking whether the sequence numbers of the received packets are consecutive, and if the sequence numbers of the received packets are not consecutive,
A step of dynamically adjusting the buffer size so that packets arriving within the average transmission time can be received; a step of storing a packet received next from the communication partner in a buffer; and a sequence of a packet received next. The procedure to check whether the numbers are consecutive, and the procedure to replace the packets in the buffer so that the sequence numbers are consecutive if the corresponding packet is found in the buffer, and the procedure to replace the packet in the buffer If the buffer has enough free space to receive the next packet, the procedure returns to the procedure for storing the next received packet in the buffer. Or reduce the amount of video data sent to the other party. Recording medium for recording a multimedia communication packet sequencing program for executing a procedure to determined the computer.